1. Field of the Invention
This disclosure is related to the field of diamond and gemstone grading. Specifically to systems and methods for evaluating the scintillation of a diamond and presenting that evaluation in a static comparative format.
2. Description of Related Art
Diamonds have traditionally been graded based on what is known as the four C's: color, clarity, carat weight, and cut. Other than carat weight which is directed to the actual size of the stone, the other three factors attempt to quantify or rank diamonds which are objectively better than others. The parameters, therefore, are ways of indicating how light interacts with the diamond, whether the stone appears bright and lively, and whether the diamond appears to produce color or not.
While the four C's have a long standing tradition, they are, in many respects, a stand in for what is a subjective appearance to a user. Instead of talking about more objective grading standards, many users instead will focus on what they see in a diamond. This may relate to color or to “liveliness” of a diamond. A well cut diamond, when moved, will often appear to include many different colors of light in a number of different locations making the stone have what appears to be a large amount of internal movement, color, and prismatic effect.
Generally, a diamond's effect on light is characterized by referring to the stone having fire, brilliance, or scintillation. All of these terms relate to the stone's ability to reflect, refract, or otherwise act on incoming light in a particular fashion. Brilliance is generally the stone's ability to redirect white light toward a viewer, scintillation is generally the apparent movement or flashing of light in the stone, and fire is generally the ability of the stone to disperse light and produce colors which appear to be within the stone. Scintillation is often colloquially referred to as “sparkle” since the flashing points of light make the gemstone appear to sparkle as it is moved.
Interestingly, cutting a diamond for one effect will often lower the ability to see other effects. For instance, a very brilliant diamond will often appear to not have much fire or scintillation. While color or movement may be being produced under certain conditions, the color and changes may be washed out by the high level of white light. Therefore, it often requires examination of a stone under many different lighting conditions to see its true attributes.
Because of the complexity of a diamond's geometry as well as the different kinds of environments in which it may be viewed, purchasing diamonds is often very frustrating for a consumer. They may look at a diamond and think it is attractive, but are concerned that what they like is not objectively “better” or that they are being overcharged for an item which is as much an investment as a purchase. For this reason, an ability to objectively evaluate and also to more systematically explain and display the properties of a particular diamond are desirable.
As the effect of scintillation is flashes of white or colored light that appear when the gemstone, the observer, or the illumination is in movement, it can often be difficult to demonstrate or quantify the scintillation of a diamond. The effect of scintillation is sometimes demonstrated to a potential purchaser by moving a gemstone under a given illumination scenario. This can provide the ability to compare the scintillation of multiple diamonds provided at a single time, but often does not allow for comparison of diamonds which are separated by physical or temporal space. Further, since the effect can be specific to lighting conditions, it often requires that the presentation be made in a live setting, which can be difficult in certain retail environments.
Further, in the jewelry industry there is generally a need to evaluate the illumination effects of brilliance, fire, and scintillation for gemstone grading purposes so that a purchaser of a diamond or other gemstone has a generally objective measure of the quality of the gemstone. This grade then needs to be provided as part of a grading document which can be provided with the gemstone to a consumer. Grading allows the user to better quantify the “value” of the diamond for purposes such as insurance, investment, and potential replacement, and also helps to create and regulate the market for gemstones by providing universal objective criteria which can be used in pricing and comparison. While a diamond grade does not necessarily reflect subjective “beauty” of a gemstone and many gemstones of low grade are undeniably beautiful, a diamond grade can be used to effect price and value comparisons that can assist with comparisons between diamonds by creating a market with objective external criteria.
The use of objective criteria to evaluate the light performance of a diamond is well known. U.S. Pat. Nos. 6,665,058; 6,795,171; 7,336,347; 7,372,552; 7,382,445; 7,355,683; 7,420,657; 7,580,118; and 7,751,034, the entire disclosure of all of which is herein incorporated by reference, all discuss methodologies and presentation methods by which various light handling properties of gemstones can be objectively evaluated and presented to a customer, retailer, or investor. However, while these methods and systems are very valuable, they primarily focus on the static (that is non-movement related) light handling properties of the gemstone such as fire and brilliance.
Scintillation has been notoriously hard to quantify in any type of fixed grading criteria because it is inherently a dynamic effect and requires relative movement. There are generally two types of scintillation, flash scintillation and fire scintillation. These are discussed in, for example, “Evaluation of Brilliance, Fire, and Scintillation in Round Brilliant Gemstones,” Optical Engineering (2007), the entire disclosure of which is herein incorporated by reference. That work defines and characterizes gemstone scintillation as follows: “In the presence of brilliance and fire the most appealing effect is gem scintillation. In this effect the fire pattern changes dynamically and flashes of white light are perceived across the crown of the stone. Thus, there are two major scintillation effects, fire and flash scintillation. To observe them it is required that the stone, the observer, or the illumination conditions be in movement.”
Because scintillation is a dynamic effect, the effect of scintillation is sometimes demonstrated by moving a gemstone under a given illumination scenario, or by computer simulation of the same. Such systems and methods are discussed in, for example, U.S. Pat. No. 8,098,369, the entire disclosure of which is herein incorporated by reference. While such systems and methods can be very useful when computational machines are available, or in live presentations, it can be difficult to provide such a scintillation evaluation in a form that is readily useable for insurance evaluation, or other record keeping on the gemstone. Typically, grading information needs to be placed on a paper document that can be provided with the gemstone to the retailer and then end consumer by a grading lab or other outside authority. Scintillation methods have generally, at best, required computer storage media with the evaluation thereon to be provided to the end consumer, and this can be undesirable for certain types of grading documents.